Public static void main(String[] args) {

A A = new A()；

system . out . println(getvalue infield(a，" b 1 "，" I "))；

system . out . println(getvalue infield(a，" b2 "，" I))；

system . out . println(getvalue infield(a，" b3 "，" I "))；

}

Public static object getValueInField (object object, string field, string name) {

//The three parameters are the object obj of the external class, the reference name of the class as a member attribute, and the attribute name of the internal class to be queried.

Try {

Object o = obj.getClass()。 GetDeclaredField (field). get(obj)；

returno.getClass()。 GetDeclaredField (name) get(o)；

Catch (exception e) {

System.out.println ("search failed");

Returns null

}

}

}

Level a

B b 1 = new b (1);

B b2 = new b (2);

}

Class b {

int I；

B(int i){

this.i = i

}

}